Internal wrench



8 5 1950 N. R. HALVORSEN 2,518,886

' INTERNAL WRENCH Filed April 1, 194a Norm an R. f/a/vors en IN V EN TOR.

BY WM ATTORNEY socket.

Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE 2,518,886 INTERNAL WRENCH Norman R. Halvorscn, Brooklyn, N. Y.

Application April 1, 1948, Serial No. 18,382

2 Claims. (01. 81-71) ated when the bolt is hidden from view, close to an inside corner or otherwise inaccessible.

Other objects will be apparent from the following description, drawings and claims.

In the drawings,

Figure 1 is an isometric view of a wrench showing the characteristics of this invention.

Figure 2 is a cross section view of the wrench head engaged in a bolt socket in driving position.

Figure 3 is a cross section view of the wrench head and bolt socket, in the position assumed when it is desired to shift the wrench handle without removing the wrench head from the socket, and without turning the bolt.

The wrench head I has upper driving surfaces 2 which are proportioned to fit closely with corresponding surfaces 3 of the hexagonal socket 4 in bolt 5.

When wrench head I is fitted in driving position into socket 4 the vertical axis of head and socket coincide.

The head has a recess 6 opposite driving surfaces 2 which provides clearance between the head and the surfaces of the socket which are diametrically opposite surfaces 2.

Said fro'nt recess 6 is shown to be bounded by an upper plane I I and a lower plane I2 which recedes from the front surface toward the axis of the head.

Immediately below 6 on head I are driving surfaces I which are proportioned to fit closely with surfaces 8 of the socket 4.

r The head I is provided with clearance surfaces 9 diametrically opposite driving surfaces 1 and below driving surfaces 2.

The proportions of these various elements are such that when the wrench head I is in driving position in socket 4, the bolt may be rotated in the usual manner by turning wrench handle I0. When, however, it is desired to turn the handle without rotating the bolt, a slight lifting of the handle will disengage driving surfaces 2, 1 from their corresponding socket surfaces, permitting the unimpeded turning of the wrench handle without removing the wrench head from the This design for a wrench head has about 50% as much driving surface as the conventional hexagonal wrench. Experiments have shown that 2 this surface is ample, when the head is heat treated steel, to exert the full locking torque on bolts without injury to either wrench head or socket.

It is obvious that this invention provides a wrench which can be used in as restricted quarters as a conventional wrench, and is no heavier than a conventional wrench. Ratchet wrenches formerly used for rapid manipulation have the disadvantages of large size, heavy weight, complex construction and high cost. All of these objections are eliminated by this invention.

The invention can of course be used to operate any device in which a prismatic socket is employed as a torque transmitter, but is primarily intended for use with conventional hexagonal socket headed bolts.

I claim:

1. A wrench head for transmitting torque to a regular prismatic socket having driving surfaces lying in regular prismatic planes, the length of said head being substantially equal to the distance between opposite parallel edges of said head, a clearance recess extending inwardly from a front driving surface at the upper portion of said head, said clearance recess comprising a lower plane which recedes from the front surface toward the axis of the head, a bottom clearance adjacent the bottom of said head and diametrically opposite the clearance recess, said clearance recess and bottom clearance being proportioned so that any dimension through the head in planes perpendicular to said lower plane is less than the distance between flats of the prism. r V

2. A wrench head for transmitting torque to a conventional hexagonal bolt socket, having driving surfaces lying in hexagonal prismatic planes, the length of said head being substantially equal to the distance between flats of the prism, a top clearance'recess extending inwardly from a front driving surface and comprising a lower plane which recedes from the front surface toward the axis of the head, a relieved bottom end of the wrench head being relieved diametrically opposite the clearance recess, said clearance recess and relieved end being so proportioned that any dimension through the head in planes perpendicular to said lower plane is less than the distance between flats of the prism.

NORMAN R. HALVORSEN.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 316,457 Great Britain Aug. 1, 1929 548,615 Great Britain Oct. 16, 1942 

